【作者】 张博；

【导师】 张晓光；

【作者基本信息】 北京邮电大学 ， 电子与通信工程（专业学位）， 2019， 硕士

【摘要】 当今信息技术的发展正迈入继专家使用期、个人计算机时代和因特网时代后的第四个阶段。世界无线研究论坛(WWRF,Wireless World Research Forum)预测,截止至2020年,全世界将有大约7万亿无线设备,也就是说,每个居民平均被1000部无线设备所包围[1]。随着移动设备数量的显著增加和应用需求的快速发展,当前的移动通信架构将很快达到极限,移动计算和云计算作为新的计算模式应运而生并出现在各种应用环境中[2]。移动云计算可看做是移动通信和无线通信技术演进与融合的结果,而随着资源集中型移动设备的普及,移动云计算服务将会在人类生活中起到更加重要的作用。移动云计算的优势在于可以充分利用云计算资源集中和移动设备的灵活性。但随着科技的快速发展,现代移动设备上需要运行越来越复杂的移动应用以满足用户的需求。随之而来的主要问题即是在移动网络中大数据量的传输问题及移动设备处理能力受限的问题。幸运的是,“微云”技术的出现解决了以上的问题。微云的核心是计算服务分流思想。在移动网络环境中,“微云”可被视为在网络边缘的小型计算中心。它可以帮助移动设备分流计算任务到“微云”服务器所提供的后端虚拟实例上。但在日渐复杂的部署环境和使用场景下,“微云”系统很容易因各种自然或人为原因宕机而变得不可用。因此,针对移动云计算系统环境的高可用性开展相关的研究是十分必要的。解决移动云计算系统高可用环境问题的核心在于保证移动云计算服务的可持续性。由于移动云计算系统的核心服务是“微云”后端虚拟服务器的计算分流功能和服务,故移动云计算高可用环境的重点即是保证该功能和服务的可持续性。传统的虚拟机服务高可用技术主要通过虚拟机迁移技术(包括冷迁移和热迁移)来实现。以此为基础所提出的“微云切换”技术也为移动云计算服务的可持续性提供了技术支撑。但由于移动云计算系统环境复杂性的快速提升,架构复杂、迁移时间较长、数据传输量较大的“微云切换”技术很难直接满足移动云计算系统高可用环境的需求。本文围绕微云三层模型的移动云计算高可用环境研究这一主题展开探究,深入学习了微云三层模型的原理和机制,从系统架构设计、数据传输量优化、服务迁移时间3个方面对传统微云切换技术进行优化,提出了一种移动云计算服务的高可用系统方案并在OpenStack云计算平台上通过实验验证了分析结果。主要研究工作如下:(1)阐述了移动云计算微云三层模型的原理和架构,并对其核心的三大技术(微云发现、微云配置、微云切换)的机制和原理进行深入研究。重点对微云切换技术的关键性技术机制和原理进行研究,为进行移动云计算高可用方案的设计打下基础。(2)对OpenStack云计算平台的架构、核心项目组件组成及功能进行介绍。设计最小微云三层模型系统和移动云计算高可用系统,实现两者在OpenStack平台上的搭建和服务验证。(3)从系统架构设计、数据传输量优化、服务迁移时间3个方面对两个系统的高可用性进行分析、实验验证和对比。结果表明,移动云计算高可用系统可以简化移动网络复杂度,大大减小服务迁移时间和迁移过程中的数据传输量,从而避免数据风暴和网络拥塞,提高移动云计算服务的网络鲁棒性和可持续性。更多还原

【Abstract】 The development of information technology is entering the fourth phase following the age of the expert,the personal computer and the Internet.Wireless Word Research Forum(WWRF)predicts that there will be around 7trillion devices in the world by 2020,in other words,each resident will be surrounded by 1000 wireless devices.With the signification increase in the number of mobile devices and the rapid development of the application requirements,the current mobile communication architecture will soon reach the limit,mobile computing and cloud computing arise as a new computing model and are applied to various application environments.Mobile cloud computing can be seen as the result of the evolution and integration of mobile communication and wireless communication technology.With the popularity of resource-intensive mobile devices,mobile cloud computing is playing an more important role.Mobile cloud computing can make full two advantages--the resource concentration of cloud computing and the flexibility of mobile devices.However,with the rapid development of technology,modern mobile devices need to run more and more complex mobile applications to meet the needs of users.Fortunately,the emergence of "cloudlet"solved the problem of the above.The core of cloudlet is the idea of distributary of computing services.In the mobile network,cloudlet can be regarded as a small computing center on the edge of the network,and it helps mobile devices to offload computing tasks to back-end VMs provided by cloudlet.However,in increasingly complex deployment environments and usage scenarios,cloudlet system can easily go down and become unavailable due to various natural or man-made factors.Therefore,it is necessary to conduct relevant research on the high availability of mobile cloud computing system environment.The core of solving the high availability environment problem of mobile cloud computing system is to ensure the sustainability of mobile cloud computing services.Since the core services of mobile cloud computing system is the computing split-flow function and service of cloudlet back-end virtual server,because the key point of mobile cloud computing high availability environment is to ensure the sustainability of this function and service.Traditional VM service high availability technology is mainly realized through VM migration technology(including cold migration and hot migration).The proposed "VM hand-off" technology based on above technologies also provides technical support for the sustainability of mobile cloud computing services.However,due to the rapid increase in the complexity of mobile cloud computing system environment,the VM hand-off with complex architecture,long migration time and large amount of data transmission is difficult to be applicable to the demand of high availability environment of mobile cloud computing system.This paper focuses on the research of mobile cloud computing,high-availability environment based on the cloudlet three-level model,deeply studies the principle and mechanism of the cloudlet three-level model,and optimizes the traditional VM hand-off technology from three aspects:architecture design,data transmission quantity and service migration time.A high-available system scheme for mobile cloud computing services is proposed and the analysis results are verified by experiments on OpenStack platform.The main research works are as follows:(1)The principle and architecture of cloudlet three-level model of mobile cloud computing are expounded,and three core technologies(Cloudlet Discovery,Rapid Just-In-Time VM Provisioning and VM Hand-Off)mechanism are deeply studied.This paper analyzes the factors affecting the high-availability of mobile cloud computing network,points out its optimization direction and implementation method,and puts forward the research and design scheme for the high availability of mobile cloud computing network.(2)The architecture and core project components and functions of OpenStack are introduced.This paper designs the minimum cloudlet three-level model system and mobile cloud computing high-availability system,and implement the system establishments and service verification of both,including services discovery,service configuration and service migration.(3)The high availability of two systems are analyzed,experimentally verified and compared from three aspects:system architecture design,data transmission and service migration time optimization.The results show that the high-availability system of mobile cloud computing can simplify the complexity of mobile network,greatly reduce the service migration time and the amount of data transmission in the migration process,so as to avoid data storm and network congestion,and improve the network robustness and sustainability of mobile computing services.更多还原